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Thread: instantaneous velocity/average velocity from looking at position graph

  1. #1
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    instantaneous velocity/average velocity from looking at position graph



    I was having trouble getting this picture to be the right size, but the left hand side y axis has values of 50,100,150
    X axis is labeled 2,4,6,8,10
    The y axis represents distance in meters, x is time in seconds.
    I am asked to order the following from least to greatest:
    A. The instantaneous velocity at time 6 seconds.
    B. The instantaneous velocity at time 9 seconds
    C. the average velocity over the interval from 6- 8 seconds.

    I know you can draw a tangent line for instantaneous velocity but this is hard for me to do with this picture.
    How should I approach this problem? the average velocity appears to be about 5/2 but that's all I can get.
    The correct answer is E and NOT A.
    Answer E got cut off but it is B<C<A
    This is an old quiz problem.
    Can someone help me understand?
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  2. #2
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    Quote Originally Posted by calc67x View Post


    I was having trouble getting this picture to be the right size, but the left hand side y axis has values of 50,100,150
    X axis is labeled 2,4,6,8,10
    The y axis represents distance in meters, x is time in seconds.
    I am asked to order the following from least to greatest:
    A. The instantaneous velocity at time 6 seconds.
    B. The instantaneous velocity at time 9 seconds
    C. the average velocity over the interval from 6- 8 seconds.

    I know you can draw a tangent line for instantaneous velocity but this is hard for me to do with this picture.
    How should I approach this problem? the average velocity appears to be about 5/2 but that's all I can get.
    The correct answer is E and NOT A.
    Answer E got cut off but it is B<C<A
    This is an old quiz problem.
    Can someone help me understand?
    The slope at B is negative; why did you not call that less than the others? They aren't asking about speed (the absolute value of velocity).

    And can you explain why you think A < B < C?

    I wouldn't bother calculating values; you can just visually estimate which is steeper. But giving numbers will help you explain your thinking.

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